U3 was a joint venture between

SanDisk SanDisk is a brand for flash memory products, including memory cards and readers, USB flash drives, solid-state drives, and digital audio players, manufactured and marketed by Western Digital. The original company, SanDisk Corporation was acquire ...

and M-Systems, producing a proprietary method of launching Windows software from special

USB flash drive A USB flash drive (also called a thumb drive) is a data storage device that includes flash memory with an integrated USB interface. It is typically removable, rewritable and much smaller than an optical disc. Most weigh less than . Since fir ...

s. Flash drives adhering to the U3 specification are termed "U3 smart drives". U3 smart drives come preinstalled with the U3 Launchpad. Applications that comply with U3 specifications are allowed to write

files File or filing may refer to: Mechanical tools and processes * File (tool), a tool used to ''remove'' fine amounts of material from a workpiece **Filing (metalworking), a material removal process in manufacturing ** Nail file, a tool used to gent ...

or registry information to the host computer, but they must remove this information when the flash drive is ejected. Customizations and settings are instead stored with the application on the flash drive.

Microsoft Microsoft Corporation is an American multinational corporation, multinational technology company, technology corporation producing Software, computer software, consumer electronics, personal computers, and related services headquartered at th ...

and

created a successor called

StartKey Startkey is a USB flash storage device developed by Microsoft and SanDisk. History StartKey began in May 2007 when Microsoft and SanDisk made an agreement to provide unspecified software to replace U3 that was included on SanDisk flash device ...

. SanDisk began phasing out support for U3 Technology in late 2009.

U3 platform

U3 disk mounting: hardware emulation

A U3 flash drive presents itself to the host system as a USB hub with a CD drive and standard

USB mass storage device The USB mass storage device class (also known as USB MSC or UMS) is a set of computing communications protocols, specifically a USB Device Class, defined by the USB Implementers Forum that makes a USB device accessible to a host computing devi ...

attached. * This configuration causes Windows disk management to show two drives: *# A read-only

ISO 9660 ISO 9660 (also known as ECMA-119) is a file system for optical disc media. Being sold by the International Organization for Standardization (ISO) the file system is considered an international technical standard. Since the specification is ...

volume on an emulated CD-ROM drive with an autorun configuration to execute the U3 LaunchPad, and; *# A standard flash drive ( FAT formatted) that includes a hidden "SYSTEM" folder with installed applications. * U3 compliant applications can be (optionally) preloaded by manufacturers.

U3 Launchpad

The U3 Launchpad (LaunchU3.exe) is a

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

program manager that is preinstalled on every U3 smart drive. The U3 Launchpad automatically starts at insertion of a U3 enabled device.

U3 applications

To be fully U3 compliant, an application has to be programmed to clean up its own data from the local machine. It must also be packaged in U3's special program format. U3 applications will only run from a U3 device. U3 programs can be downloaded from the U3 website and other places. Applications include

Opera Opera is a form of theatre in which music is a fundamental component and dramatic roles are taken by singers. Such a "work" (the literal translation of the Italian word "opera") is typically a collaboration between a composer and a libre ...

and

Skype Skype () is a proprietary telecommunications application operated by Skype Technologies, a division of Microsoft, best known for VoIP-based videotelephony, videoconferencing and voice calls. It also has instant messaging, file transfer, ...

and do not need to be installed on the computer.

APIs

The U3 application programming interfaces (APIs) allow U3 programs lower-level access to USB flash drive, and to query the drive letter. The U3 APIs primarily allow developers who choose to use more of the power of U3 to control how their application handles things like device removal and saves data back to the drive such as configuration or documents.

Compatibility

The latest version of U3 launchpad supports

Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft and oriented towards businesses. It was the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and was official ...

with Service Pack 4,

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was release to manufacturing, released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Wind ...

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...

Windows 7 Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was released to manufacturing on July 22, 2009, and became generally available on October 22, 2009. It is the successor to Windows Vista, released nearl ...

and

Windows 8 Windows 8 is a major release of the Windows NT operating system developed by Microsoft. It was released to manufacturing on August 1, 2012; it was subsequently made available for download via MSDN and TechNet on August 15, 2012, and later to ...

. Data can be accessed using any OS capable of reading from USB mass storage devices, unless the U3 device is password-protected.

Issues with older versions

Early versions of the U3 launchpad software had Vista compatibility issues (specifically the SanDisk Cruzer Titanium series with device numbers 2.17, 2.18, 2.19 and 2.20), although this problem could be eliminated by updating the launcher software. Prior to Sandisk's updated launcher software being released, Microsoft supported U3 by releasing an update to Vista.

Developer resources

Information on building U3 compliant applications and the U3

software development kit A software development kit (SDK) is a collection of software development tools in one installable package. They facilitate the creation of applications by having a compiler, debugger and sometimes a software framework. They are normally specific ...

were available to registered developers at the official U3 website. Individuals must register (as a company) to download the SDK, or participate in the forums. Applications that do not require installation steps in order to run can easily utilize U3 with little or no modification by taking steps to either not modify the host systems files or registry, or undoing all changes when the application terminates. A wizard which packages distribution files and creates the special "manifest" file is provided. As of May 2009, the software development kit was no longer available; the u3.com website is no longer available.

Removal

Reformatting the drive will remove some of the software (the hidden "SYSTEM" folder), but not all of it. The virtual CD-ROM drive cannot be removed by reformatting because it is presented to the host system as a physical device attached to a USB hub; the official U3 Launchpad Removal Software was available on the U3 website and disabled the virtual CD drive device, leaving only the

active on the U3 USB hub controller, at which point the remaining software can be removed by a subsequent format, performed by the removal software itself. ''u3_tool'' is another option that includes the ability to remove the virtual CD-ROM drive, as well as ways to reconfigure it to the user's liking.

Criticism

Numerous criticisms have been made of the U3 platform. These criticisms are: ;Malware-like integration behaviour: Software comes preinstalled on USB disk and, when using stock Windows settings, roots itself in the system similar to malware. U3 removal is possible, but requires complete data backup. ;Questioned use: There are already portable versions of many Windows software available, some of which do not require any proprietary solution to work. ;Removed user data, but not all of it: Recent files and programs had it listed. ;Freezing with certain CD writing software: There is a possibility of slowing down or freezing Windows XP Pro if certain Windows drivers that are associated with high-volume data transfers to CD writers using certain CD/DVD burning software installed. ;Proprietary format/closed platform: The U3 platform is a "closed" platform /

proprietary format A proprietary file format is a file format of a company, organization, or individual that contains data that is ordered and stored according to a particular encoding-scheme, designed by the company or organization to be secret, such that the decod ...

, the rightsholders for U3, ask for a 5% royalty from USB flash drive manufacturers who wish to implement the platform on their products. ;Two drive letters: As a work-around to the lack of Auto-Play for Flash drives on older versions of Windows, the U3 software creates two drive letters (one which presents itself as a CD to allow Windows' auto-play to start the launcher, and another for storing user data). Although this is the only way to implement auto-start functionality on pre-Windows XP systems, it could be considered a

kludge A kludge or kluge () is a workaround or quick-and-dirty solution that is clumsy, inelegant, inefficient, difficult to extend and hard to maintain. This term is used in diverse fields such as computer science, aerospace engineering, Internet sl ...

, and the extra drive letter created can be an annoyance. However, it is possible to prevent Windows from allocating a drive letter for the "CD drive" via the Windows "Disk Management" tool—as long as the user has the appropriate rights/authority to do so. ;Incompatibility with certain embedded systems: Some host systems – such as photo kiosks, consumer electronics, and other embedded computing devices – cannot correctly mount U3 "smart drives." The problem may arise because the emulated CD-ROM is the first drive presented to the host system. As such, the device is detected as a CD-ROM drive or not at all. Although some newer photo kiosks are U3 aware and can overcome this limitation, it still exists on many platforms.

Notes

References

External links

* * {{cite web , url=https://www.pcmag.com/article2/0,2817,1861681,00.asp , title=Full Preview - U3 Preview , date=2005-09-21 , author=Ben Z. Gottesman , publisher= PC Magazine
u3-tool
open source u3 managing tool USB Proprietary package management systems Companies established in 2004 Portable software Portable software suites SanDisk products